Every year, millions of patients are treated for life-threatening emergencies in the United States. Such emergencies include shock, trauma, cardiac arrest, drug overdoses, diabetic ketoacidosis, arrhythmias, burns, and status epilepticus just to name a few. For example, according to the American Heart Association, more than 1,500,000 patients suffer from heart attacks (myocardial infarctions) every year, with over 500,000 of them dying from its devastating complications. In addition, many wounded soldiers die unnecessarily because intravenous (IV) access cannot be achieved in a timely manner. Many soldiers die within an hour of injury, usually from severe bleeding and/or shock.
An essential element for treating all such emergencies is the rapid establishment of an IV line in order to administer drugs and fluids directly into the circulatory system. Whether in the ambulance by paramedics, in the emergency room by emergency specialists or on the battlefield by an Army medic, the goal is the same—to start an IV in order to administer life-saving drugs and fluids. To a large degree, the ability to successfully treat such critical emergencies is dependent on the skill and luck of the operator in accomplishing vascular access. While it is relatively easy to start an IV on some patients, doctors, nurses and paramedics often experience great difficulty establishing IV access in approximately 20 percent of patients. The success rate on the battlefield is much lower where Army medics are only about 29 percent successful in starting an IV line during emergency conditions in the field. These patients are probed repeatedly with sharp needles in an attempt to solve this problem and may require an invasive procedure to finally establish an intravenous route.
In the case of patients with chronic disease or the elderly, the availability of easily-accessible veins may be depleted. Other patients may have no available IV sites due to anatomical scarcity of peripheral veins, obesity, extreme dehydration or previous IV drug use. For these patients, finding a suitable site for administering lifesaving drugs becomes a monumental and frustrating task. While morbidity and mortality statistics are not generally available, it is known that many patients with life-threatening emergencies have died of ensuing complications because access to the vascular system with life-saving IV therapy was delayed or simply not possible. For such patients, an alternative approach is required.
The intraosseous (IO) space provides a direct conduit to the systemic circulation and, therefore, is an attractive alternate route to administer IV drugs and fluids. Intraosseous infusion has long been the standard of care in pediatric emergencies when rapid IV access is not possible. The military used hand-driven IO needles for infusions extensively and successfully during World War II, but the needles were cumbersome, difficult to use, and often had to be driven into the bone. Drugs administered intraosseously enter the circulation as rapidly as they do when given intravenously. In essence, the bone marrow is considered to be a large non-collapsible vein.
Although effective in achieving IO access, the currently available IO infusion devices suffer from several significant limitations. Current devices are single-use only and bulky, which limits the number of devices a medic can take into the field. Manually inserted IO needles are very difficult to use in hard adult bones. Current devices frequently penetrate not only the anterior bone cortex, but may also the posterior cortex. In addition, some current devices pose a significant risk of shattering the bone upon use. After the needle is inserted, many current devices suffer from a high rate of dislodgement from the bone because of the non-axial manner in which they must be inserted. Dislodgement often leads to extravasation (leakage of fluid from the entry points of the needle).